EP4067744A1 - Grate bar assembly and method for operating a grate bar assembly - Google Patents

Abstract

In a grate bar arrangement with a plurality of grate bars, each with a running surface and a grate bar head, in which an upper grate bar with its grate bar head is arranged so that it can move relative to a lower grate bar in such a way that the grate bar head can slide over a front and a rear area of the running surface of the grate bar the running surface has air slots in the front and rear area and the grate bar head can be displaced relative to these air slots in such a way that the opening cross section of all the air slots remains constant.

Description

The invention relates to a grate bar arrangement with a plurality of grate bars, each with a running surface and a grate bar head, in which an upper grate bar with its grate bar head is arranged so that it can move relative to a lower grate bar in such a way that the grate bar head can slide over a front and a rear area of the running surface of the grate bar .

Furthermore, the invention also relates to a method for operating a grate bar arrangement with a plurality of grate bars, each with a running surface and a grate bar head, in which an upper grate bar with its grate bar head is moved relative to a lower grate bar in such a way that the grate bar head extends over a front and a rear area of the running surface of the grate bar slides.

Grate firing is solid fuel firing in which the fuel lies on a grate and burns. The grate is an apertured surface. The openings in the grate are used to supply the air required for combustion ("downdraft") and the ash is discharged via a deslagger. In the case of larger grate furnaces, the necessary movements for circulating ("stoking") the fire take place automatically by moving the grate.

A stair grating/gravel grating looks similar to a flat-lying stair with a slope typically between 0 and 30, such as 24 or 26 degrees. The fuel is moved over the grate by the steps moving and thus transporting the fuel. Depending on the direction of the grate bar movement, the stepped grate is also called a feed grate or a reverse feed grate (in both cases, however, the fuel moves forward).

Step grates are used for lumpy and ash-rich fuels that require improved stoking, e.g. B. household and commercial waste, biomass, processed waste or today less often lignite.

Stepped grates have a large number of grate bars, which can be firmly connected to one another or can be moved relative to one another in order to move the material to be burned on the grate.

Grate bars usually have air slots in front of the running surface in a grate bar head. For this purpose, recesses or in the form of round openings in the surface are provided on the side wall of the grate bar, which allow air to be conveyed to the underside of the grate bar, which can then escape between grate bars through the air slot to the combustion bed. However, it is also possible, for example, to provide round openings in the surface of the grate bar.

Especially when treating waste with a high metal content, metal parts in the area of the grate bar head can get caught in the air slots and become stuck.

To avoid this, the EP 2 614 304 A1 Air slots, which are arranged in the side walls of the grate bar in the area of the grate bar head and the running surface. Since these air slots are arranged on both sides of the grate bar, the built-in grate bar has recesses opposite each other, which together form an air slot. With a relative movement of adjacent grate bars, particles that have penetrated the air slots are cut up and comminuted in such a way that they are conveyed back into the combustion bed by the air flow in the air slots.

However, this arrangement has the disadvantage that the forces acting on metal particles in the air slots also cause counter-forces which act on the individual grate bars and can result in uncontrolled movements of the grate bars and also damage in the area of the air slots.

A grate bar is not used as a single grate bar in the operation of a combustion plant, but as a grate bar arrangement with several grate bars. An upper grate bar with its grate bar head is arranged so that it can move relative to a lower grate bar in such a way that the grate bar head can slide over a front and a rear area of the running surface of the grate bar. In such a grate bar arrangement, it is provided that the running surface has air slots in the front and rear area and the grate bar head can be displaced relative to these air slots in such a way that the opening cross section of all the air slots remains constant.

This means that by shifting the grate bars relative to each other, all air slots of the grate bar below are temporarily covered by the grate bar above, sometimes only the front air slots and sometimes no air slots at all are covered by the grate bar above. As a result, more or less air initially flows through the grate bar below. However, since more or fewer air slots are also covered on the overlying grate bar during the movement of the grate bar by the grate bar arranged above it, the opening cross section of all air slits is constant in the arrangement according to the invention.

In the case of a grate with several rows of grate bars lying one above the other, there are many areas in which there is a grate bar arrangement with several grate bars which are arranged and movable in such a way that the opening cross section of all ventilation slots of this grate bar arrangement remains constant. The air slots are arranged in such a way that the same free area is always available for air passage, resulting in alternating air distribution and leading to stable firing. The relative stroke of the grate bars lying one on top of the other leads to air slots that can be driven over and a cutting free of disruptive particles that can collect in the area of the air slots.

In this case, grate bars arranged one above the other can be moved relative to one another, and grate bars arranged next to one another can either be movable relative to one another or can also be firmly screwed together.

The invention is therefore based on the object of further developing such known grate bars in order to protect the grate bars in practical operation and to achieve a defined aeration of the combustion bed.

In terms of process, the object on which the invention is based is achieved with a method for operating a grate bar arrangement with a plurality of grate bars, each with a running surface and a grate bar head, in which an upper grate bar is moved with its grate bar head relative to a lower grate bar in such a way that the grate bar head over a front and a rear area of the running surface of the grate bar slides. The running surface has air slits in the front and rear area and the grate bar head is displaced relative to these air slits in such a way that the opening cross section of all air slits remains constant. This grate bar arrangement need not contain all the grate bars of the furnace. It is sufficient if these grate bars are arranged in a region of several grate bars arranged one above the other and are provided with air slots in such a way that the opening cross section of all the air slots remains essentially constant even during operation.

The object on which the invention is based is also achieved with an arrangement with a grate bar, in which the at least one air slot is arranged only on one side wall and not in the opposite side wall.

Due to the fact that air slots are only arranged on one side wall, it is impossible for particles to penetrate into the area of opposite air slots and be exposed to a shear stress which acts on at least one grate bar. The arrangement of the air slots in the area of the running surface and not in the area of the grate bar head ensures that a grate bar lying above it, which is on the Tread sliding exerts a force on metal particles that get caught in an air slot.

The shearing effect therefore does not act between two adjacent grate bars, but rather between a grate bar below, where particles may penetrate into the air slot, and a grate bar above, which slides on the running surface and thus also pushes out particles that have penetrated an air slot .

When the grate bar head of the grate bar arranged above it runs over the air slots arranged in the running surface, this ensures that the air slit is at times in the combustion bed and is at times covered by the grate bar above. This reduces thermal wear on the louver. In addition, when the grate bar head of the grate bar sliding over the air slot runs over it, the running surface is cleaned or at least pushed free. This also cleans the top of the air slot. In the area of the air slots, the fire is fueled by the supplied air. This can result in so-called forge fires, which lead to thermal wear, particularly in the area of the air slots. A special advantage lies in the fact that these forge fires are extinguished by the upper grate rod head driving over them. The air slots are even briefly covered by the grate bar head moving over them, so that they can cool down a bit. But even after that, the air slots that have been driven over can continue to cool down, since the burning material above them has been pushed away.

Since according to the invention the overlying grate bar in the area of the running surface of the underlying grate bar clears the air slots of particles caught therein, it is further proposed that the side wall has at least one air slot only in the area of the running surface. The grate bar no longer has any air slits in the area of the grate bar head and either one air slit is provided in the area of the running surface or several air slits are provided one behind the other. preferably two air slots are arranged one behind the other in the area of the tread.

If there are no air slots in the area of the grate bar head, no air slots are pushed into the combustion bed with the grate bar head. This prevents material, such as metal particles in particular, from being pressed into air slots in the grate bar head when the grate bar head is moved into the combustion bed.

In order to further reduce the risk of metal parts getting caught in the air slots of the grate bar, it is proposed that the air slot have a cross-sectional area which widens from the running surface to the underside. The air slot thus widens from the upper running surface to the underside below and this means that particles that get from the combustion bed and thus from the running surface into the air slot can fall down through the air slot if they are passed through an over the be pressed into the air slot or cut by the upper grate bar guided by the running surface.

For this purpose, there can also be a cutting edge between the running surface and the area underneath which has an enlarged cross-sectional area, which cut edge facilitates the comminution of a particle entering the air slot.

An air slot is generally formed with a front side directed transversely to the extent of the grate bar and opposite a rear side and a side wall lying in between. In this case, it is advantageous if the front, the rear and/or the side wall are arranged at an acute angle to the tread, so that on the one hand the cross-sectional area expands directly under the tread and on the other hand an edge is created on the tread that prevents particles from being cut up favored.

In practice, the lower end of the grate bar head lies on the running surface of a grate bar below and the sliding surface of the upper grate bar head touches the running surface of the grate bar below. This sliding surface can Have clearing bar, which is shaped so that it acts with a defined force on particles that are on the tread or possibly something have penetrated into the air slots.

Accordingly, the clearing strip can have a contact surface extending at an acute angle or an arc with a radius of less than 200 mm and in particular around a circular sector of less than 80° to the sliding surface as the cutting edge. This cutting edge can be arranged in the longitudinal direction of the grate bar at the front end of the sliding surface in order to cut off, scrape off or advance material from the surface of the grate bar underneath when the grate bar is advanced over a running surface of a grate bar underneath.

However, the cutting edge can also be arranged at the rear end of the sliding surface in order to clean the surface of the underlying running surface with the cutting edge when the upper grate bar is pulled back relative to the running surface of an underlying grating bar, over which the sliding surface of the overlying grating bar is pulled. Preferably, the grate bar head thus has two cutting edges which clean the running surface of a grate bar located underneath when the grate bar is advanced and retracted.

However, the sliding surface of the grate bar can also have a clearing strip which, as a thrust edge, has a contact surface extending at an obtuse angle or an arc with a radius of more than 200 mm and in particular around a sector of a circle of more than 100° to the sliding surface. This thrust edge can also be formed on the front area of the sliding surface and/or on the rear area of the sliding surface in order to allow the sliding surface of the grate bar head to slide safely over such deposits even if the running surface under the grate bar head is dirty.

A particularly preferred embodiment has a cutting edge in the front area of the sliding surface and a pushing edge in the rear area of the sliding surface. je Depending on the design of the grate and depending on the material to be burned, the grate bar can have a cutting edge or a thrust edge at different points and different grate bars can also be combined in order to use the optimal grate bar in different combustion areas, the thrust and has cutting edges. This allows grate bars to be individually adapted to the combustion process, which leads to optimal combustion.

Irrespective of the features mentioned above, the grate bar according to the invention can also have a bar that is in one or two parts. A one-piece bolt is understood to mean a bolt that is not cast or welded on, but as a bolt is a removable part. This bar can be arranged positively or non-positively on a side wall of the grate bar. For example, it can have a head that is inserted into a slot and is fixed by twisting.

The bolt is preferably in two parts and in particular designed as a combination of screw and nut. Therefore, it is suggested that the latch of the grate bar has a screw. This enables easy dismantling of grate bars, especially in the edge area of the combustion bed. The nut that can be screwed on can lie under the running surface or on the outside next to the running surface. Preferably, the screw head is on the outside and the nut is protected under the tread.

A special variant provides that the screw of the bolt has a head that has a polygonal socket. The screw can then be, for example, a so-called Allen screw, a hexagon socket or a square socket. The head of the screw is preferably located on a side wall in such a way that it protrudes outwards over the side wall and takes over the function of the bolt, while a nut is arranged below the running surface and only serves to hold the screw and, if necessary, to replace the screw.

In the case of a removable bolt, the head of the bolt forms the function of the known bolt, since this head extends into a bolt window of an adjacent grate bar can intervene. It is advantageous if this head has a round cross section, since then no disruptive material can collect on the bolt. The round surface of the bar no longer forms a level on which disruptive material agglomerates.

A grate bar can also have several bars at different points on the grate bar. However, it is advantageous if the grate bar has only one bar, since then the problems arising at the bar are also reduced to one problem area.

While in the prior art internals such as cooling fins are generally arranged on the underside of the grate bar, it is proposed that the underside between the side surfaces in the area of the bolt is essentially flat. This allows a counterpart of the latch, such as a nut, to be placed in an easily accessible location and the entire grate bar requires less material and ultimately weighs less.

Another advantageous feature of the grate bar is that it has a latch window into which a latch of an adjacent grate bar can engage and which has an opening on the side opposite the running surface. This embodiment is intended for the edge bars, since there it is not necessary to hold the grate bar down, i.e. to secure it against lifting.

The transom window thus has an opening at the bottom through which material that gets into the transom window can fall out of the transom window again.

The feature that the grate bar has a core bar that is cast into the grate bar is also essential to the invention, independently of the aforementioned features. Although there are known grate bars made of different materials. These grate bars have a special material on the running surface, while the rest of the grate bar is made of a different material. This enables particularly stable running surfaces.

However, a core bar cast into the grate bar has a different function. It can be designed to be particularly ductile, so that it does not also break if the bar breaks, or at least still holds the fragments of the bar together in such a way that the bar cannot fall down. This means that the grate can continue to be operated even if the grate bar is broken until the next controlled standstill, without the grate missing a broken bar that has fallen into the hopper below.

Figur 1

einen Roststab mit einem vorderen und einem hinteren Riegel,

Figur 2

eine vergrößerte Darstellung des in Figur 1 gezeigten vorderen Riegels,

Figur 3

einen Schnitt durch zwei Roststäbe im Bereich des in Figur 2 gezeigten Riegels,

Figur 4

eine vergrößerte Darstellung einer alternativen Ausführungsform zum in Figur 2 gezeigten Riegel,

Figur5

einen Schnitt durch zwei Roststäbe im Bereich des in Figur 4 gezeigten Riegels,

Figur 6

eine Ansicht einer Roststabanordnung mit drei nebeneinander liegenden Roststäben,

Figur 7

eine Ansicht einer Roststabanordnung mit jeweils zwei nebeneinander und zwei übereinander angeordneten Roststäben,

Figur 8

einen Schnitt durch einen Roststabkopf mit vorne einer Schnittkante und hinten einer Schubkante,

Figur 9

einen Schnitt durch einen Roststabkopf mit vorne einer Schnittkante und hinten einer erhöhten Schnittkante,

Figur 10

einen Schnitt durch einen Roststabkopf mit vorne einer Schnittkante und hinten einer nach unten weisenden Schnittkante,

Figur 11

schematisch einen Ausschnitt aus Figur 1 mit dem vorderen Luftschlitz,

Figur 12

schematisch einen Längsschnitt durch den in Figur 11 gezeigten Bereich des Roststabes,

Figur 13

schematisch einen Querschnitt durch den in Figur 11 gezeigten Bereich des Roststabes,

Figur 14

schematisch ein vergrößertes Detail aus Figur 13,

Figur 15

eine Roststabanordnung mit einem beweglichen Roststab in der untersten Position,

Figur 16

die in Figur 15 gezeigte Roststabanordnung mit dem beweglichen Roststab in einer mittleren Position,

Figur 17

die in Figur 15 gezeigte Roststabanordnung mit dem beweglichen Roststab in der obersten Position,

Figur 18

die Unterseite eines Roststabes,

Figur 19

einen Längsschnitt durch den in Figur 18 gezeigten Roststab,

Figur 20

schematisch einen in einen Roststab eingegossenen Kernstab und

Figur 21

den in Figur 20 gezeigten Roststab in gebrochenem Zustand.

Exemplary embodiments of grate bars and grate bar arrangements are shown in the drawing and are described in more detail below. It shows

figure 1

a grate bar with a front and a rear latch,

figure 2

an enlarged view of the in figure 1 shown front latch,

figure 3

a cut through two rust bars in the area of the in figure 2 shown bar,

figure 4

an enlarged view of an alternative embodiment to in figure 2 shown bars,

Figure5

a cut through two rust bars in the area of the in figure 4 shown bar,

figure 6

a view of a grate bar arrangement with three adjacent grate bars,

figure 7

a view of a grate bar arrangement with two grate bars arranged side by side and two grate bars arranged one above the other,

figure 8

a section through a grate bar head with a cutting edge at the front and a thrust edge at the back,

figure 9

a section through a grate rod head with a cutting edge at the front and a raised cutting edge at the rear,

figure 10

a section through a grate bar head with a cutting edge at the front and a cutting edge pointing downwards at the rear,

figure 11

schematically a section figure 1 with the front air vent,

figure 12

schematically a longitudinal section through the in figure 11 shown area of the grate bar,

figure 13

schematically a cross-section through the in figure 11 shown area of the grate bar,

figure 14

schematically shows an enlarged detail figure 13 ,

figure 15

a grate bar arrangement with a movable grate bar in the lowest position,

figure 16

in the figure 15 shown grate bar arrangement with the movable grate bar in a middle position,

figure 17

in the figure 15 shown grate bar arrangement with the movable grate bar in the uppermost position,

figure 18

the bottom of a grate bar,

figure 19

a longitudinal section through the in figure 18 shown grate bar,

figure 20

schematically a core bar cast into a grate bar and

figure 21

the in figure 20 shown rust bar in broken condition.

the inside figure 1 The grate bar 1 shown has a grate bar head 2, two side walls 3 and 4 and a running surface 5. In a front area of the grate bar 1 is the grate bar head 2 and behind it is the running surface 5 in a rear area of the grate bar 1. Below the running surface 5 lies between the Side walls 3 and 4 the underside 6 of the grate bar 1.

In the area of the running surface 5, there are recesses 7 and 8 on one side of the grate bar 1 in the side wall 4. These laterally arranged recesses 7 and 8 form air slots 9, 10 running from the underside 6 to the running surface 5 in a view transverse thereto.

The air slots 9 and 10 are only arranged in the area of the running surface 5 and not in the area of the grate bar head 2 . As a result, the air slots 9, 10 are completely run over by a grate bar head pushed onto the running surface 5 of another grate bar.

The front flank 11 and the rear flank 12 of the air slot 9 are each arranged at an acute angle to the running surface 5, so that the cross-sectional area 13 (cf. figure 6 ) from the running surface 5 to the underside 6 of the grate bar 1 expanded.

Accordingly, the flanks 15, 16 of the air slot 10 - as in figure 12 shown - arranged at an acute angle 17, 18 to the running surface 5, so that the cross-sectional area 14 of the air slot 10 from the running surface 5 to the underside 6 also expands there.

The enlargement of the cross sections 13 and 14 from the running surface 5 to the underside 6 of the grate bar 1 is also reinforced by the fact that the recesses 7 and 8 are arranged between the flanks 11 and 12 or 15 and 16 at an acute angle to the running surface 5 that the cross-sectional area 13, 14 of the air slots 9, 10 widens from the tread 5 to the underside 6.

the figure 6 shows how several grate bars 1, 21, 22 are arranged next to one another in order to provide running surfaces 5, 23, 24 essentially in one plane with air slots 25 to 28 in between.

the figure 7 shows how on the running surfaces 5 and 23 of the grate bars 1 and 21 the grate bar heads 29 and 30 of other grate bars 31 and 32 slide along. The grate rod heads 29 and 30 move through the air slots 9, 10 and 27 and 28 of the Grate bars 1 and 21 to push material lying on the running surfaces 5 and 23 combustion bed from the air slots 9, 10 and 27 and 28 away.

For this purpose, the front end of the grate rod head 2, 29, 30 has a special shape, depending on the application and application - as in the Figures 8, 9 and 10 shown in cross section - can be formed.

the inside figure 8 The grate head 33 shown has a lower end 34 with a sliding surface 35 which has a cutting edge 37 at the front end of the grate head 33 . This cutting edge 37 has an acute angle 38 between the sliding surface 35 and a thrust surface 36.

When the grate rod head is pulled back, the inside 40 serves as a clearing bar, which is figure 8 shown embodiment is formed in the transition to the sliding surface 35 as a thrust edge 41. This thrust edge 41 has an obtuse angle 42 between the sliding surface 35 and a thrust surface 40 . while the figure 8 has as a thrust edge 41 an arc with a radius of about 6 mm and a circular sector of about 105 °, shows the figure 9 a cutting edge 46 on the grate bar head 45 - as in figure 8 - And as a thrust edge 41 in cross section training as a corner with an obtuse angle.

the figure 10 shows a grate bar head 50 with a cutting edge 51 with an acute angle 52 in the front area of the sliding surface 53 and another cutting edge 54 with an acute angle 55 in the rear area of the sliding surface 53 of the grate bar head 50.

the Figures 2 to 5 show two-part bolts 60, 61, each consisting of a screw 62, 63 and a nut 64, 65. The screw 62 has a screw head 66 with a polygonal socket 67 and the screw 63 has a mushroom-shaped screw head 68 . In both cases, the bolt 60, 61 has a bolt head with a round cross-section, which is either arranged in the wall of the adjacent grate bar ( figure 3 ) or under the underside 69 of the adjacent grate bar is arranged ( figure 5 ). The undersides 6 and 69 of adjacent grate bars 1 and 23 are essentially flat between the side walls 3 and 4 in the area of the bolts 60 and 61, so that the screws 62 and 63 and the nuts 64 and 65 are easily accessible.

Each grate bar 1, 23 has a transom window 70, 71 on one side wall 3 and a transom 60, 61 on the opposite side wall 4, so that when grate bars 1, 23 are next to each other, a transom 60, 61 can be inserted into the transom window 70, 71 of the adjacent one Latch can intervene. The bolt window 70, 71 can accommodate the bolt 60, 61 of the adjacent grate bar in the upper area and have an opening (not shown) on its side opposite the running surface 5.

The in the Figures 18 to 21 The grate bar shown has only a single bolt 66 and a core bar 80 is cast into the grate bar 1 . This cast-in core rod 80 lies under the tread in such a way that it does not touch the tread. Cast in means that the core bar is preferably completely surrounded by the remaining material of the grate bar and is therefore completely encased by other material.

the figure 21 shows how the core bar 80 bends when the grate bar 1 breaks and how it bridges this gap 81 in the event of a gap 81 occurring during the break and how the broken parts 82, 83 of the grate bar 1 are held together.

the Figures 15 to 17 show a grate bar arrangement 90 with two fixed grate bars 91 and 92 and a movable grate bar 93 arranged between them Figures 15 to 17 can be seen how the movable grate bar 93 between the fixed grate bars 91 and 92 from the in figure 15 shown lower position over the in figure 16 middle position shown in the in figure 17 shown upper position can be pushed.

The arrangement and design of the grate bars are designed in such a way that, regardless of the position of the movable grate bar 93, the opening cross section of all the air slots 94 to 97 remains constant. The grate bars 91 and 93 have a running surface for this 98, 99 and one grate bar head 100, 101 each, and the grate bar 93 is arranged as the upper grate bar with its grate bar head 101 movable relative to the grate bar 91, which serves as the lower grate bar. When the upper grate bar 93 is pushed over the lower grate bar 91, the grate bar head 101 slides over a front area 102 and a rear area 103 of the running surface 98 of the grate bar 91. First, the air slot 95 in the rear area 103 is run over by the grate bar head 101 of the grate bar 93, so that the air slot 95 then - as in figure 16 shown - is covered by the grate bar head 101 of the grate bar 93. However, the air slot 96 in the grate bar 93, which was previously covered by the grate bar 92, is uncovered. Thus, in the in figure 15 shown grate bar position the air slots 94 and 95 open, while in the Fig figure 16 position shown the air slots 94 and 96 are open.

the figure 17 shows the grate bar 93 pushed completely upwards, which now covers both the air slot 95 and the air slot 94 of the grate bar 91. The air slots 96 and 97 of the movable grate bar 93 are uncovered here, so that two air slots are also exposed again in this position of the movable grate bar 93 .

This example of a grate bar arrangement shows how the arrangement of the air slots 94, 95, 96, 97 in the area of the running surfaces 98, 99 makes it possible to ensure that the opening cross section of all air slots remains constant during the movement of the grate bars.

Claims (12)

Grate bar arrangement (90) with several grate bars (91, 92, 93), each with a running surface (98, 99) and a grate bar head (100, 101), in which an upper grate bar (93) with its grate bar head (101) relative to a lower grate bar (91) is movably arranged in such a way that the grate bar head (101) can slide over a front area (102) and a rear area (103) of the running surface (98, 99) of the grate bar (91), characterized in that the running surface (98, 99) has air slots (94, 95, 96, 97) in the front and rear area (102, 103) and the grate bar head (100, 101) can be displaced in this way relative to these air slots (94, 95, 96, 97). is that the opening cross section of all air slots (94, 95, 96, 97) remains constant. Grate bar arrangement according to Claim 1, characterized in that grate bars (1, 21, 22) arranged next to one another can be moved relative to one another Grate bar arrangement according to Claim 1 or 2, characterized in that grate bars (1, 23) arranged next to one another are firmly screwed together. Grate bar arrangement according to one of claims 1 to 3 with a grate bar (1) with a grate bar head (2), two side walls (3, 4), a running surface (5) behind the grate bar head (2) between the side walls (3, 4) and a between the side walls (3, 4) underneath the running surface (5), with a recess (7, 8) in a side wall (4) between the running surface (5) and the underside (6) when two identical structures interact grate bars forms an air slot (9, 10), characterized in that the at least one air slot (9, 10) is arranged only on one side wall (4) and not in the opposite side wall (3) thereof. Grate bar arrangement according to Claim 4, characterized in that the side wall (4) has at least one air slot (9, 10) only in the region of the running surface (5). Grate bar arrangement according to one of Claims 4 or 5, characterized in that the air slot (9, 10) has a cross-sectional area (13) which widens from the running surface (5) to the underside (6). Grate bar arrangement according to one of Claims 4 to 6, characterized in that the grate bar head (2, 33) has a sliding surface (35) as the lower end (34) with a cutting edge (37) which has an acute angle (38) or an arc with a radius of less than 200 mm and in particular a circular sector of less than 80° between the sliding surface (35) and the thrust surface (36). Grate bar arrangement according to one of Claims 4 to 7, characterized in that the grate bar head (2) has a sliding surface (35) as the lower end with a thrust edge (41) which has an obtuse angle (42) or an arc with a radius of more than 200 mm and in particular a circular sector of more than 100° between the sliding surface (35) and the thrust surface (40). Grate bar arrangement according to one of Claims 4 to 8, characterized in that it has a core bar (80) which is cast into the grate bar (1). Grate bar arrangement according to one of Claims 4 to 9, characterized in that the at least one air slot (9, 10) is arranged only on one side wall (4) and not in its opposite side wall (3). Method for operating a grate bar arrangement with a plurality of grate bars (91, 92, 93), each with a running surface (98, 99) and a grate bar head (100, 101), in which an upper grate bar (93) with its grate bar head (101) relative to a lower grate bar (91) is moved in such a way that the grate bar head (101) slides over a front area (102) and a rear area (103) of the running surface (98, 99) of the grate bar (91), characterized in that the running surface ( 98, 99) in the front and in the rear (102, 103) air slots (94, 95, 96, 97) and the grate bar head (100, 101) relative to these air slots (94, 95, 96, 97) is shifted in such a way that the opening cross section of all air slots (94, 95, 96, 97) remains constant. Method according to Claim 11, characterized in that the displacement of the grate bars (91, 92, 93) relative to one another temporarily allows all the air slots (94, 95, 96, 97) of a grate bar (91) located below to be closed by the grate bar (93) located above are covered, sometimes only the air slots (94, 96) in the front area (102) and sometimes no air slots (94, 95, 96, 97) are covered by the overlying grate bar (93), so initially more or less air through flows through the grate bar (91) below, while more or fewer air slots (94, 95, 96, 97) also appear on the grate bar (93) above during the movement of the grate bar (93) through the grate bar (92) arranged above it. be covered.

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